In manufacturing of laminated cores, for example, Patent Literature 1 discloses a technique that permanent magnets are inserted respectively in plural magnet insertion holes of a rotor core body (i.e., a laminated core with no permanent magnet sealed inside) and then are resin-sealed. However, in the technique of Patent Literature 1, after resin-sealing to the laminated core is completed, it is time-consuming and troublesome to remove resin from a mold. Thus, the technique of Patent Literature 1 is not suitable for mass production.
To overcome the above problem, Patent Literature 2 discloses a technique (commonly known as a magnet molding) that a preheated rotor core body with permanent magnets inserted in magnet insertion holes is clamped between an upper mold and a lower mold, and liquefied resin is extruded from resin reservoir pots formed vertically through the upper mold, thereby being filled into the magnet insertion holes. This technique allows easy removal of eventually unnecessary cull (resin residue), remarkably increasing production efficiency.
Furthermore, Patent Literature 3 discloses a technique that a dummy plate (hereinafter called as “cull plate”) is placed on an upper part of a rotor core body, resin is injected through the cull plate, and the cull plate is removed after the resin filled in magnet insertion holes is cured. This technique enables easier removal of resin remained and cured on an upper part of a laminated core.